scholarly journals Industry-Oriented Method for Dynamic Force Identification in Peripheral Milling Based on FSC-LSQR Using Acceleration Signals

Author(s):  
Maxiao Hou ◽  
Hongrui Cao ◽  
Qi Li ◽  
Jianghai Shi

Abstract Online measurement of milling force play a vital role in enabling machining process monitoring and control. In practice, the milling force is difficult to be measured directly with the dynamometer. This paper develops a novel method for milling force identification called least square QR-factorization with fast stopping criterion (FSC-LSQR) method, and the queue buffer structure (QBS) is employed for the online identification of milling force using acceleration signals. The convolution integral of milling force and acceleration signals is discretized, which turns the problem of milling force identification into a linear discrete ill-posed problem. The FSC-LSQR algorithm is adopted for milling force identification because of its high efficiency and accuracy, which handles the linear discrete ill-posed problem effectively. The online identification of milling force can be realized using the acceleration signal enqueue and the milling force dequeue operations of the QBS. Finally, the effectiveness of the method is verified by experiments. The experimental results show that the FSC-LSQR algorithm running time is within \((0.05s)\) and the calculation error is less than \((10\%)\). The proposed method can make the sampling frequency of the milling force reach 10240Hz by employing QBS, which satisfy the industry requirements of milling force measurement.

Author(s):  
Chenxi Wang ◽  
Xingwu Zhang ◽  
Baijie Qiao ◽  
Hongrui Cao ◽  
Xuefeng Chen

Dynamic milling forces have been widely used to monitor the condition of the milling process. However, it is very difficult to measure milling forces directly in operation, particularly in the industrial scene. In this paper, a dynamic force identification method in time domain, conjugate gradient least square (CGLS), is employed for reconstructing the time history of milling forces using acceleration signals in the peripheral milling process. CGLS is adopted for force identification because of its high accuracy and efficiency, which handles the ill-conditioned matrix well. In the milling process, the tool with high-speed rotation has different transfer functions between tool nose and accelerometers at different angular positions. Based on this fact, the averaged transfer functions are employed to reduce the error amplification of regularization processing for milling force identification. Moreover, in order to eliminate the effect of idling and high-frequency components on identification accuracy, the Butterworth band-pass filter is adopted for acceleration signals preprocessing. Finally, the proposed method is validated by milling tests under different cutting parameters. Experimental results demonstrate that the identified and measured milling forces are in good agreement on the whole time domain, which verifies the effectiveness and generalization of the indirect method for milling force measuring. In addition, the Tikhonov regularization method is also implemented for comparison, which shows that CGLS has higher accuracy and efficiency.


2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Nengjian Wang ◽  
Chunping Ren ◽  
Chunsheng Liu

This paper presents a novel inverse technique to provide a stable optimal solution for the ill-posed dynamic force identification problems. Due to ill-posedness of the inverse problems, conventional numerical approach for solutions results in arbitrarily large errors in solution. However, in the field of engineering mathematics, there are famous mathematical algorithms to tackle the ill-posed problem, which are known as regularization techniques. In the current study, a novel fractional Tikhonov regularization (NFTR) method is proposed to perform an effective inverse identification, then the smoothing functional of the ill-posed problem processed by the proposed method is regarded as an optimization problem, and finally a stable optimal solution is obtained by using an improved super-memory gradient (ISMG) method. The result of the present method is compared with that of the standard TR method and FTR method; new findings can be obtained; that is, the present method can improve accuracy and stability of the inverse identification problem, robustness is stronger, and the rate of convergence is faster. The applicability and efficiency of the present method in this paper are demonstrated through a mathematical example and an engineering example.


Procedia CIRP ◽  
2018 ◽  
Vol 77 ◽  
pp. 18-21 ◽  
Author(s):  
Chenxi Wang ◽  
Xingwu Zhang ◽  
Baijie Qiao ◽  
Xuefeng Chen ◽  
Hongrui Cao

Author(s):  
Andre D. L. Batako ◽  
Valery V. Kuzin ◽  
Brian Rowe

High Efficiency Deep Grinding (HEDG) has been known to secure high removal rates in grinding processes at high wheel speed, relatively large depth of cut and moderately high work speed. High removal rates in HEDG are associated with very efficient grinding and secure very low specific energy comparable to conventional cutting processes. Though there exist HEDG-enabled machine tools, the wide spread of HEDG has been very limited due to the requirement for the machine tool and process design to ensure workpiece surface integrity. HEDG is an aggressive machining process that requires an adequate selection of grinding parameters in order to be successful within a given machine tool and workpiece configuration. This paper presents progress made in the development of a specialised HEDG machine. Results of HEDG processes obtained from the designed machine tool are presented to illustrate achievable high specific removal rates. Specific grinding energies are shown alongside with measured contact arc temperatures. An enhanced single-pole thermocouple technique was used to measure the actual contact temperatures in deep cutting. The performance of conventional wheels is depicted together with the performance of a CBN wheel obtained from actual industrial tests.


2014 ◽  
Vol 800-801 ◽  
pp. 243-248
Author(s):  
Kai Zhao ◽  
Zhan Qiang Liu

When machining the complex parts of aircraft engines, the milling force for the circular contour must be accurately predicted to reduce machining vibration. In this paper, the prediction model of the mean milling force per tooth during machining circular contour is developed. Firstly, the formulas of the entry angle, the exit angle and the equivalent feed per tooth are established through the analysis of circular contour milling process. Then, the equation of the mean milling force per tooth is deduced based on mechanistic force model during the circular contour machining process. Finally, the prediction model of mean milling force per tooth during machining circular contour is developed using MATLAB programming. The relationship between the milling force per tooth and surface curvature radius of the machined workpiece is also analyzed in this paper.


2005 ◽  
Vol 291-292 ◽  
pp. 67-72 ◽  
Author(s):  
M. Ota ◽  
T. Nakayama ◽  
K. Takashima ◽  
H. Watanabe

There are strong demands for a machining process capable of reducing the surface roughness of sliding parts, such as auto parts and other components, with high efficiency. In this work, we attempted to grind hardened steel to a mirror-like surface finish with high efficiency using an ultra-high speed grinding process. In the present study, we examined the effects of the work speed and the grinding wheel grain size in an effort to optimize the grinding conditions for accomplishing mirror-like surface grinding with high efficiency. The results showed that increasing the work speed, while keeping grinding efficiency constant, was effective in reducing the work affected layer and that the grinding force of a #200 CBN wheel was lower than that of a #80 CBN wheel. Based on these results, a high-efficiency grinding step with optimized grinding conditions was selected that achieved excellent ground surface quality with a mirror-like finish.


2004 ◽  
Vol 471-472 ◽  
pp. 825-829
Author(s):  
Wen Ge Wu ◽  
Si Qin Pang ◽  
Qi Xun Yu

Reversible cutting method is a research thesis proposed to shorten processing route, decrease tool number and handling time, increase machining efficiency. There are three movement ways, i.e. reversible feed motion, reversible primary motion and reversible composite motion. Primary motion is done by workpiece, conventional or reversible feed motion is done by cutting tool in the way of reversible feed motion, e.g. turning. Cutting velocity is passed to cutting tool, clockwise or anti-clockwise cutting movement is done by cutting tool in the way of reversible primary motion, e.g. milling, shaping, drilling (spade drill), reaming. Primary and feed motions are all reversible in composite motion, e.g. turn-milling. Chip deformation and machined surface with reversible finishing is discussed. A mechanical analysis is carried out to the workpiece deformation of slender shaft turning in normal direction and reversible direction. The result has been verified by experiments. Experimental data for the range of cutting parameters tested showed that the reversible fine machining produce the compressive residual stresses at the surface, which are critical in the performance of the machined components. Experimental research indicted that the results of micro-hardness of reversible fine machining technique are smaller than that of general fine machining show that decreased plastic deformation of the surface layer and work-hardening. It can be adopted such planning which rough machining during advance stroke and fine machining during return stroke in machining process.


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